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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Crash on invalid on NVRO within template instantiation"
href="https://bugs.llvm.org/show_bug.cgi?id=51708">51708</a>
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<th>Summary</th>
<td>Crash on invalid on NVRO within template instantiation
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Frontend
</td>
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<th>Assignee</th>
<td>mizvekov@gmail.com
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<th>Reporter</th>
<td>rtrieu@google.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<pre>This crash was first observed at this revision:
<a href="https://github.com/llvm/llvm-project/commit/f2d5fce86e81a8b37fbc0829a1c68b6eb48f8365">https://github.com/llvm/llvm-project/commit/f2d5fce86e81a8b37fbc0829a1c68b6eb48f8365</a>
As seen in the test case below, the crash happens when the VarDecl being tested
for NVRO is invalid during template instantiation.
Testing shows that in TemplateDeclInstantiator::VisitVarDecl, if the call to
SemaRef.getNamedReturnInfo is skipped when Var->isInvalidDecl(), then the crash
can be avoided. Although a better fix would be to handle invalid Decl's when
checking alignment.
$ cat test.ii
template <class>
class a
;
template <typename b>
b f() {
b d;
return d;
}
auto e = {
f< a< int > >() };
$ clang test.ii
test.ii:10:3: error: implicit instantiation of undefined template 'a<int>'
f< a< int > >() };
^
test.ii:2:7: note: template is declared here
class a
^
test.ii:5:3: error: implicit instantiation of undefined template 'a<int>'
b f() {
^
test.ii:10:3: note: in instantiation of function template specialization
'f<a<int>>' requested here
f< a< int > >() };
^
test.ii:2:7: note: template is declared here
class a
^
test.ii:6:5: error: implicit instantiation of undefined template 'a<int>'
b d;
^
test.ii:2:7: note: template is declared here
class a
^
clang/lib/AST/RecordLayoutBuilder.cpp:3256: const clang::ASTRecordLayout
&clang::ASTContext::getASTRecordLayout(const clang::RecordDecl *) const:
Assertion `D && "Cannot get layout of forward declarations!"' failed.</pre>
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